1. Field of the Invention
The present invention relates to a magnetic sensor, a magnetic head, and a magnetic memory by using spin Hall devices.
2. Description of the Related Art
It has been found that electron has charge imparting electric conductivity, spin imparting magnetic property, and three degrees of internal freedom of orbital representing spatial extension of the electron and their interaction provides new properties for a material. In order to exhibit new functions by controlling the degrees of internal freedom of electrons, which are not considered in conventional electronics, instead of a semiconductor device using charge possessed by electrons, attention is being focused on the development of spintronics materials and devices actively using the property of electron spin that is achievable from the correlation of magnetic property and conductivity as mentioned in Spin Dependent Transport in Magnetic Nanostructures, edited by S. Maekawa and T. Shinjo (Taylor Francis, N.Y., 2002). Information of electron spin or spin orbital spatially depends on a ratio of a distance L and a spin diffusion length λ and attenuation is exponentially made according to exp(−L/λ). Accordingly, a spatial scale in which the property of electron spin or spin orbital is exhibited is limited to the same level as that of the spin diffusion length. However, with the development of micro-processing technology, a spin injection device has been proposed as a tunnel magnetoresistance device using spin injection in a magnetic nanostructure system having the level of the spin diffusion length λ as mentioned in F. J. Jedema et al., “Electrical Detection of Spin Precession in a Metallic Mesoscopic Spin Valve”, 2002, Nature, Vol. 416, p. 713.
U.S. Pat. No. 6,403,999 discloses that when a magnetic field or electromagnetic field is applied to a semiconductor in a stacked structure of the semiconductor, an insulating layer (Al2O3), and a magnetic layer (NiFe), a Hall voltage by spin polarization electrons injected from the magnetic layer to the semiconductor is detected.
A device disclosed in the document by the F. J. Jedema et al. is based on the effect of magnetoresistance whose resistance varies with an external magnetic field applied to a metal or semiconductor. To obtain higher magnetoresistance, a GMR device has a stacked structure of a magnetic layer/nonmagnetic metal layer/magnetic layer and a TMR device has a structure stacked in order of a magnetic layer/insulator layer/magnetic layer. In this magnetic multi-layer film structure, since plural magnetic layers are present in a signal read path using a memory and a sensor, the effect of magnetic noise resulting from thermal fluctuation of magnetization of the magnetic layer increases, thereby making it difficult to improve sensitivity.
In U.S. Pat. No. 6,403,999, a method for detecting a Hall voltage by spin polarization electrons injected from the magnetic layer to the semiconductor is disclosed, but a configuration or method for detecting a direction in which the magnetic layer is magnetized by an external magnetic field is not disclosed.